1. Field of the Invention
The present invention relates to a surface light-emitting type semiconductor light-emitting device such a double hetero LED or a laser, to an LED head including the semiconductor light-emitting device, to an image-forming apparatus including the semiconductor light-emitting device, and to a method of manufacturing the semiconductor light-emitting device.
2. Description of the Related Art
A semiconductor light-emitting device wherein a light-reflecting film, semiconductor light-emitting layer and anode electrode are laminated successively on an electrically conducting plate (cathode electrode) has been proposed in, for example, Japanese Patent Application Laid-Open Publication No. 2002-217450 (pp. 5-7, FIG. 1), which is referred to “Patent Reference 1.” This semiconductor light-emitting device has a surface light-emitting construction wherein light which has been generated in an active layer of the semiconductor light-emitting device and radiated through all azimuths, is directly or after reflection via a light-reflecting film, extracted via the main surface on the anode electrode side of the semiconductor light-emitting layer.
However, if an optically reflecting surface (in Patent Reference 1, the light-reflecting film and the anode electrode) is formed on both surfaces of the semiconductor light-emitting layer, interference may occur due to the superimposition of the light rays generated in the active layer which pass through the main surface of the semiconductor light-emitting layer, and the light rays generated in the active layer which pass through the main surface of the semiconductor light-emitting layer after being reflected by the optically reflecting surfaces on both sides of the semiconductor light-emitting layer. As a result, the light extracted from the main surface of the semiconductor light-emitting layer has a different spectral distribution (i.e., a spectral distribution wherein a specific wavelength is stronger and another specific wavelength is weaker) from natural light emission. Under the conditions where such interference occurs, the spectral distribution largely varies due to scatter in the film thickness of the semiconductor light-emitting layer or the reflectivity of the optically reflecting surfaces, and therefore there is a large scatter in the light-emitting properties of the semiconductor light-emitting device due to manufacturing error.